J. Phys. IV France 01 (1991) C4-71-C4-76
A CALORIMETRIC INVESTIGATION OF MARTENSITIC TRANSFORMATION UNDER APPLIED STRESS IN SINGLE-CRYSTAL Cu-AL-Ni ALLOYSC.M. FRIEND1, Ll. MANOSA2, J. ORTÍN2 and A. PLANES2
1 Materials Technology Group, Cranfield Institute of Technology, Shrivenham Campus, Swindon, Great-Britain
2 Departament d'Estructura i Constituent de la Matèria, Faculta de Fisica, Universitat de Barcelona, Catalonia, Spain
A high sensitivity microcalorimeter is described which is capable of carrying out measurements on samples subjected to uniaxial tensile stress. This novel calorimeter was used, together with stress-free calorimetry, to map the composition dependence of the martensite phase-stabilities in four Cu-Al-Ni alloys. It is shown that stress-temperature phase diagrams produced using this approach are extremely interesting since they contain phase boundaries which were previously inaccessible during stress-induced transformation experiments. Direct calorimetric determinations of the enthalpy and entropy changes during β → γ' transformation are also presented for the four alloys, and the effect of applied stress on the enthalpy and entropy changes during both β → γ', and β → β' transformation are analysed for one of the alloys.
© EDP Sciences 1991